Previous clinical observations have suggested that with increased age, decremental changes in salivary gland function occur. It is the purpose of this project to investigate, in an animal model, biochemical factors which regulate salivary gland function and study their operation and regulation with increased age. Initial focus has been on mechanisms involved in protein secretion from the rat parotid gland, particulary the role of beta-adrenergic receptors, cyclic AMP and cyclic AMP-dependent protein kinase.